1. Field of the Invention
This invention relates to electronic monitoring and tracking of persons. More particularly, it refers to a system for providing advanced warning to victims and concurrently delivering immediate instructional commands to offenders, and timely notification to an offender supervising and law enforcement agency should an offender and victim come within an unallowable proximity of one another.
2. Description of Prior Art
Determining the location of a person or subject, such as an offender or victim, is possible outside the confines of their respective residence according to the method described in U.S. Pat. No.5,731,757. The apparatus employed in the method is a tamper resistant body worn ankle wireless transmitter communicating with an associated tamper resistant portable tracking apparatus. The portable tracking apparatus determines its location using Global Positioning System (GPS) satellites. The portable tracking apparatus communicates with a central data base system using wireless communications when portable, and using land-line communications when placed in a charging stand at the subject's residence or work location. Algorithms in the offender's portable tracking apparatus executing on the processor compare the offender's current location against a schedule of location rules stored in the memory of the offender's portable tracking apparatus.
In order to provide dynamic safety perimeters for the victim (i.e. a safety perimeter that moves with the victim), both the offender's portable tracking apparatus and the victim's portable tracking apparatus must establish frequent wireless communication connections with the central data base system to maintain a location, health and status, hereinafter defined as heartbeat, to support location data fusion processing at the central data base system. Frequent wireless communication connections to the central data base system are required since the central data base system performs the location data fusion processing necessary to determine violation of the victim's dynamic safety perimeters as the location of the victim changes. The central data base system also notifies victims, supervising agencies and law enforcement agencies regarding the health and status of the offender's portable tracking apparatus and body worn device.
Other prior art portable locating apparatus using satellite signals and providing notification based on a location do not consider the issues of latency of data transfer or cost effective wireless data transfer associated with subject collision avoidance using a wireless portable locating apparatus. Such apparatus can be seen in U.S. Pat. Nos. 5,594,425, 5,627,548, and 5,497,149.
Another approach to obtaining location, health and status is to poll the offender's and victim's portable tracking apparatus by placing a cellular phone call to the apparatus as described in U.S. Pat. No. 5,461,390. This centralized polling approach increases notification time to the victim. Frequent cellular phone calls to the offender and victim portable tracking apparatus determines location, health and status. This will incur significant wireless cost.
In the prior art, a central data base system is responsible for a location data fusion processing and notifications. This requires multiple communication sessions in order to report violations to victims' supervising agencies and law enforcement agencies. A single point of failure in such multiple communication sessions results in total system failure.
Recently, digital wireless services have incorporated packet message capability which do not require establishing a full duplex (i.e. two-way) connection between a sender and a receiver before transferring digital information. The industry term for this type of analog or digital wireless service is called connectionless oriented service. An example of an implemented connectionless oriented wireless service is cellular digital packet data (CDPD). Devices that commonly use CDPD and other forms of connectionless oriented services are alphanumeric pagers, two way alphanumeric pagers and wireless personal communication services (PCS) such as mobile data terminals and mobile fax machines.
Currently, Transport Connection Protocol/Internet Protocol (TCP/IP) packets are used to route wireless data packets from source to destination. Since the allocation of a send and receive wireless channel for a typical connection oriented full duplex communication session supporting ring, answer, data transfer and hang-up is not required for packetized connectionless oriented analog or digital wireless services, the data transfer is faster, shorter in duration and more cost effective. Devices that support connectionless oriented analog or digital wireless services include pagers, digital cellular phones and PCS devices. TCP/IP packets can also be routed between the wireless network, private land based networks, public switched telephone networks and the Internet enabling devices attached to the Internet, a public network or a private network to communicate directly with wireless devices and the portable tracking device referenced in U.S. Pat. No. 5,731,757.
The problem with a connectionless oriented analog or digital wireless message is that there is no end-to-end verification that a message is successfully delivered since there is only a half duplex (i.e. a transmit channel) connection between the source and destination for the message. This problem is further compounded for wireless applications because wireless media is less reliable and more susceptible to interference than wire or fiber optic media. Forward error correction, as is known in the art, can detect and correct some interference problems, but dropped packets due to severe interference or equipment failures between source and destination cannot be recovered.
There exists a need to reduce the wireless connection time between a subject's (i.e. offender or victim) portable tracking apparatus and a central data base system to provide more timely location, health and status data (i.e. heartbeat) in a cost-effective manner. In the case of an offender and associated victims, there exists a need for the offender's portable tracking apparatus and victim's portable tracking apparatus to communicate location, health and status data directly to each other rather than only relying on being relayed through the central data base system. The portable tracking apparatus also needs to perform location data fusion processing to eliminate the latency time and wireless communications cost associated with location data fusion processing being performed at a central data base system using multiple connection oriented circuit switched wireless communications. In the case of offender violation notifications to offender supervising agencies, law enforcement agencies and victims, there exists a need for direct communications between an offender's portable tracking apparatus and notification devices (i.e. pagers, digital cellular phones, mobile data terminals, etc.) with supervising agencies, law enforcement agencies and victims. In the case of notifications generated by a victim's portable tracking apparatus to offender supervising agencies and law enforcement agencies, there exists a need for direct communications between a victim's portable tracking apparatus and notification devices (i.e. pagers, digital cellular phones, mobile data terminals, etc.) with supervising agencies and law enforcement agencies. In the case of assured message delivery, end-to-end verification of data delivery is needed to assure victims are warned, supervising and law enforcement agencies are notified and the central data base system stores offender and victim location, health and status data, especially where violations have occurred.